1. Field of the Invention
The present invention relates generally to an improvement in or relating to exhaust gas heat recovery boiler, and more particularly to an improved exhaust gas boiler for recovering heat generated from exhaust gas from a variety of heat generating means such as a gas turbine, a diesel engine, a cement baking furnace, and the like.
2. Description of the Prior Art
It is a typical construction of a conventional exhaust gas combustion boiler such that there are disposed a plurality of superheaters and reheaters in a side-by-side relationship with each other, yet not arranged in divisional stages in the upstream of an exhaust gas flow in the flow passage of an exhaust gas boiler. Also, it is known in construction of such an exhaust gas boiler that there is provided an evporator in the downstream of these superheaters and reheaters, and an economizer disposed in the further downstream of the exhaust gas flow.
With such a common construction, it is designed that an exhaust gas at a high temperature from combustion may exchange heat with the superheaters, the reheaters, the evaporator and the fluid passing in the economizer so that is is ccooled off while flowing from the area where there are provided the superheaters and the reheaters down to the low pressure side where the economizer is disposed, thereafter flowing outwardly from the boiler. Feed water is supplied from a water supply pump or the like through a water feed pipe up to the economizer, where feed water is heated by exhaust gas. Thus-heated feed water is then delivered to a water vapor drum. Part of feed water within the vapor drum is directed to the evaporator, where it is reheated by exhaust gas to be a phase of vapor-water mixture, which is returned to the vapor drum. Vapor-water mixture fluid thus-returned is then separated into vapor and water, which vapor is superheated by exhaust gas in the superheater to a high temperature and high pressure vapor which is to be fed to the steam turbine. Vapor fed to the steam turbine works to drive it in rotation, thereafter being discharged out of the turbine, and then fed to the reheater, where it is superheated again to be vapor which is either to be fed to the lower pressure stage of the steam turbine to work in driving the same or to be used as vapor for miscellaneous use.
With the conventional exhaust gas boiler of such a typical construction as reviewed hereinbefore, there were such inconveniences in practice that it was not feasible to attain a due distribution of exhaust gas into a superheater and a reheater, and a due control on a superheating temperature of vapor to be superheated by way of the superheater and the reheater, and also to feed vapor of stable pressure and temperature to the steam turbine.
In consideration of such inconveniences in use which are particular to the conventional exhaust gas boiler arrangement, there is a desire to provide an efficient resolution therefor.
The present invention is essentially directed to the provision of a due and proper resolution to such inconveniences and retrictions as reviewed above and experienced in practice of these conventional arrangement, which have been left unattended with any proper countermeasures so far.